Dental implants are implanted into the jawbone of a patient that has lost some or all of his or her teeth in that jawbone. In a common procedure for implanting dental implants, CT (CBCT-DICOM files) data and optical scan (STL files-STereoLithography) data regarding the precise location of the teeth, gums and bone in the patient's mouth are collected at some point prior to the surgery where an implant surgeon or restorative dentist implants the dental implants into the patient's mouth. These data are used with dental implant case planning software to plan the surgery during which dental implants will be implanted. This planning includes the fabrication of a surgical guide to be placed in the patient's mouth during the surgery. The surgical guide is often horseshoe-shaped (like the shape of one arch of teeth), and made of a thermoplastic or non-thermoplastic resinous base. This planning also includes a surgical protocol for the preparation of each site in the patient's jawbone where a dental implant will be implanted. The protocol provides detailed information regarding the preparation of each implant site, including information about the proper sequence of drill bits to be used at each site, and the selection of tube adapter sleeves (described further below) to be used at each site. The surgical guide and protocol are often prepared by a dental implant manufacturer, a supplier of dental implant case planning software, or a dental laboratory.
In use, the surgical guide is removably affixed in the patient's mouth using techniques known to those skilled in the art. The surgical guide rests on the patient's gums and intact teeth and has openings showing the precise locations where each dental implant is to be implanted. Each opening is defined by a guide tube, which is a ring that is often made of titanium. Following the protocol, for each implant site, the surgeon or dentist attaches a first tube adapter sleeve (having a specific size and orientation) to the guide tube of the surgical guide, and then places a drill with a first drill bit (having a specific size) through the first tube adapter sleeve and drills a hole in the jawbone having a size and orientation determined by the surgical guide, the first tube adapter sleeve and the first drill bit. This is the first step in the drilling of the hole in the jawbone into which the dental implant will ultimately be implanted. The surgeon or dentist then removes the drill and first drill bit, and attaches a second tube adapter sleeve (having a slightly larger size than the first tube adapter sleeve) to the opening in the surgical guide, and uses a second drill bit, slightly larger than the first drill bit, to make the hole in the patient's jawbone slightly larger. The process of using progressively larger tube adapter sleeves and drill bits continues until the hole in the patient's jawbone has the size called for by the surgical protocol. In a typical process, the surgeon or dentist may start with a 2 mm drill bit, and then progress to a 3 mm and then a 4 mm drill bit, with the guide tube having a diameter of 5 mm.
At this point, the hole in the patient's jawbone is ready to have the dental implant implanted into it. The dental implant is then often attached to an implant mount (or holder). The implant mount protrudes up from the patient's jawbone when a dental implant is being inserted into the jawbone, and provides a member to which the surgeon or dentist can attach a hand-piece, a drill or ratchet device when screwing the implant into the jawbone. The implant mount has a lower shaft that has the same diameter as the opening in the surgical guide defined by the guide tube. The dental implant (attached to the implant mount) is then inserted through the opening in the surgical guide defined by the guide tube, and screwed into the hole in the patient's jawbone that has been created through use of the drill bits and tube adapter sleeves described above. The implant mount has a flange at the top of the shaft that controls the depth that the dental implant is screwed into the jawbone. The flange is wider than the opening in the surgical guide defined by the guide tube. The implant mount is screwed into the jawbone until the flange comes into contact with the top of the guide tube portion of the surgical guide, which signals that the implant mount has been screwed in to the proper depth.
The top of the dental implant often has an interlocking mechanism (such as an internal hexagon-shaped opening) that must be rotated to a proper rotational position (e.g., with the flat sides of the internal hexagon-shaped opening in a specific rotational position). One technique for trying to ensure that the implant ends up in the proper rotational position is to place vertical lines or notches on both the implant mount and the surgical guide, which are lined up with one another when the implant mount is in the proper rotational position. See, e.g., U.S. Pat. No. 8,414,296 B2 at column 9, lines 31-47. However, this technique has several limitations. First, a visual inspection of both the implant mount and the surgical guide is necessary, which may be difficult, especially when the dental implant is to be implanted in the posterior of the mouth, and which depends heavily on operator evaluation and experience to avoid over-rotating the implants. Second, the implant mount may be over-rotated in an effort to get the lines to vertical lines or notches to line up, which may cause compression, warping and/or fracture of the surgical guide, and thus inaccurate placement in any of the three axes of both the implant attached to the implant mount that was over-rotated, and any additional implants to be implanted with that surgical guide. When implants are not rotated to their proper rotational position, much additional time and effort is needed to fabricate a prosthesis (whether it be a single prosthetic tooth or a prosthesis including a full arch of prosthetic teeth) to be attached to the dental implants. Thus, there exists a need in the art for an improved technique for ensuring that dental implants are rotated to their proper rotational position when they are being screwed into the jawbone.
One example of a conventional procedure for using a surgical guide to first drill a hole in a patient's jawbone and then implant a dental implant into that hole is described in Nobel Biocare's NobelGuide™: Concept manual for guided surgery.